The present invention relates to a plastic lens formed by the injection molding and to a production method thereof.
The plastic lens is used for, for example, an optical system for optical pick-up apparatus and cameras. When such the plastic lens is molded by the injection molding, at least a gate portion which is a resin injection path, is integrally formed with the plastic lens at the time of molding.
The integrally formed gate portion at the molding, is cut from the plastic lens and removed after that. Conventionally, as shown in FIG. 12, the plastic lens in which a gate-cut plane 100b formed when the gate portion 100a integrally formed at the time of the molding of the plastic lens 100 is cut, is linear, or as shown in FIG. 13, the gate-cut plane 100b is arc-shaped along the outer periphery of the plastic lens, is well known.
Further, as shown in FIG. 14, a plastic lens 100 in which a gate-cut plane 100b formed by cutting a gate portion 100a is made to be the same arc-shaped as the plastic lens as shown in FIG. 13, and further, at a different position from the gate-cut plane 100b, a gate position indicating section 100c showing the gate-located position is formed, is known.
In this connection, in the plastic lens formed such the injection molding, generally, the un-uniformity of the molecular orientation or inner distortion is generated due to the injection molding, and when the plastic lens is rotated around the optical axis of the plastic lens, the optical performance of the lens is changed. Accordingly, for example, when the mounting position of the plastic lens to each kind of optical system or apparatus is not constant for the plastic lens rotational direction, the performance among products are not stable even in the same optical system or same apparatus, and there is a case where a desired optical characteristic can not be obtained.
Accordingly, the mounting position is made constant, for example, on the basis of a portion corresponding to a position at which the gate portion of the plastic lens existed (hereinafter, called gate-located position), however, in the gate-cut plane 100b which is linear as shown in FIG. 12, or the arc-shaped gate-cut plane 100b along the outer periphery of the plastic lens as shown in FIG. 13, specifically for the down sizing of the plastic lens, the more the width of the flange portion of the plastic lens is reduced, or the more the diameter of the plastic lens is decreased, the more the gate-cut plane of the plastic lens is difficult to be distinguished from the outer periphery of the other plastic lens, and problems in which the gate-located position or the central gate-located position which is the central portion of the gate portion can not be detected, and the detection accuracy is lowered, and the operability of the assembling is lowered, occur.
On the one hand, in the plastic lens shown in FIG. 14, a gate position indicating section 100c showing the gate-located position is formed at a position different from the gate-cut plane 100b, and when the detection of the gate position indicating section 100c is easy, and the positional relationship with the gate-located position of the gate position indicating section 100c is clear, the assembling position can be made constant on the basis of the gate position indicating section 100c, however, when the gate position indicating section is provided on the position as shown in FIG. 14, it is also difficult for the operator who generally looks the plastic lens from the optical axis direction (the direction along the optical axis) to detect the gate position indicating section, and it is also difficult to correspond to it by using the conventional commonly used detector, and there is also a problem that it is yet insufficient to obtain the plastic lens which has the easily assembling operability unless the easiness of detection is increased, further, without decreasing the detection accuracy. Further, there is also a problem that the new detector to detect the gate position indicating section is necessary, and the production cost of the product is increased.
Furthermore, when the gate position indicating section is provided as a recess, because it is difficult to provide a recess by the molding die from the problem of the durability and the accuracy of the molding die of the lens, a process to newly provide the gate position indicating section is necessary. Therefore, the problems that the production cost is increased, and the time necessary for the production becomes long, occur.
Further, when the gate position indicating section is provided as a protrusion, the following problem occurs. When the gate position indicating section of the gate portion of the plastic lens is cut, it is preferable to use the masking so that the chip does not adhere onto the lens surface, however, a problem that, when the protrusion exists, the masking is difficult, and the chip adheres onto the lens surface, occurs.
The present invention is attained in view of such the problems, and the object of the present invention is to provide a plastic lens by which an object to make the detection of the gate-located position of the plastic lens easy, and to increase the detection accuracy, and an object that the lens can be easily assembled in a desired direction and the optical performance is stabilized, can be stood together, and to provide a production method thereof. Further, the object is to provide the plastic lens and the production method thereof, by which, because the cutting of the gate-located position and the display of the gate-located position can be conducted in the continuous or the same process, the production can be conducted quickly and at low cost. Further, the object is to obtain the plastic lens by which, even when the lens is a small sized one, the gate portion can be easily cut, and there is no flaw in the optical function portion, and the stable optical performance can be obtained. Further object is to obtain the plastic lens which can be stably held.
In order to solve the above problems and attain the objects, the invention is structured as follows.
(1-1) A plastic lens molded through a gate in a molding process, comprises
a gate-located portion on an outer peripheral surface of the plastic lens, and
a concave surface provided on at least a part of the gate-located portion.
(1-2) In the plastic lens of (1-1), a form of the concave surface is concave when the form is viewed along an optical axis of the plastic lens.
(1-3) In the plastic lens of (1-1), the concave surface is provided onto an entire surface of the gate-located portion.
(1-4) In the plastic lens of (1-1), the concave surface is provided on at least a part of the gate-cut surface in the gate-located portion.
(1-5) In the plastic lens of (1-4), the gate-cut-out surface other than the concave surface is shaped in a flat surface or an arc-shaped convex surface.
(1-6) In the plastic lens of (1-4), the gate-cut-out surface is the concave surface.
(1-7) In the plastic lens of (1-1), the plastic lens further comprises:
an optical function section to perform an optical function;
wherein the concave portion is provided on an outer peripheral surface of the optical function section.
(1-8) In the plastic lens of (1-1), the plastic lens further comprises:
an optical function section to perform an optical function and
a flange section;
wherein the concave portion is provided on an outer peripheral surface of the flange section.
(1-9) In the plastic lens of (1-1), a distance between an imaginary peripheral surface on the concave portion and a bottom of the concave portion has the shortest distance of 0.15 mm to 0.25 mm.
(1-10) In the plastic lens of (1-1), an angle formed between a line connecting a bottom section of the concave portion to an optical axis of the plastic lens with a shortest distance and a line connecting a center of the gate-located portion to the optical axis with a shortest distance is not larger than 10 degrees.
(1-11) In the plastic lens of (1-1), the concave surface is a curved surface.
(1-12) In the plastic lens of (1-11), a form of the curved surface is shaped an arc when the form is viewed along an optical axis of the plastic lens.
(1-13) In the plastic lens of (1-12), the arc is a part of a circle whose radius is not larger than 1 mm.
(1-14) A method of manufacturing a plastic lens, comprises steps of:
forming the plastic lens through a gate by an injection molding, wherein a gate portion occupied in the gate is formed integrally on an outer periphery of the plastic lens during the step of forming the plastic;
cutting out the gate portion from the outer periphery of the plastic lens; and
providing a concave surface on at least a part of a gate-located portion on the outer periphery of the plastic lens before, during or after the step of cutting the gate portion.
Further, the above object may be attained by the following preferable structures.
(2-1) In a plastic lens having a flange portion on the outer periphery of an optical function portion, the plastic lens in which at least a gate-located portion of the flange portion is the concave surface.
According to the invention described in (2-1), because the gate-located portion including the gate-located position of the flange portion is the concave surface, and the position is definite by the concave surface, when the plastic lens is assembled in the optical apparatus, the detection of the concave surface by eyes or the detector can be easily conducted, thereby, the detection accuracy of the gate-located position is increased. Therefore, the plastic lens can be easily and accurately assembled in the constant direction on the basis of the concave surface, thereby the assembling operability is increased, and the optical performance is stabilized.
(2-2) In a plastic lens having a flange portion on the outer periphery of an optical function portion, the plastic lens in which the flange portion has at least a gate-cut plane, and at least one portion of the gate-located portion of the gate-cut plane is the concave surface.
(2-3) The plastic lens described in (2-2), in which all the gate-located portion is the concave surface.
(2-4) The plastic lens described in (2-2) or (2-3), in which the gate-cut plane other than the concave surface is the plane or arc-shaped convex surface.
(2-5) The plastic lens described in (2-3), in which all the gate-cut plane is the concave surface.
According to the invention described in (2-2) to (2-5), because at least one portion of the gate-located portion of the gate-cut plane of the flange portion is the concave surface, or all of the gate-located portion is the concave surface, the gate-cut plane other than the concave surface is the plane or arc-shaped convex surface, or all of the gate-cut plane is the concave surface, and the gate-located position is definite by the concave surface, when the plastic lens is assembled in the optical apparatus, the detection of the concave surface can be easily conducted by eyes and the detector, thereby, the detection accuracy of the gate-located position is increased. Therefore, the plastic lens can be easily and accurately assembled in the constant direction on the basis of the concave surface, thereby the assembling operability is increased, and the optical performance is stabilized.
Further, according to the invention described in (2-4), because, in the gate-cut plane other than the concave surface, the shape is the plane or the arc-shaped convex surface and different from the other portion, the gate-located position from the optical axis of the plastic lens becomes definite, and the gate-located position becomes definite also from the side surface of the plastic lens, thereby, the detection accuracy of the gate-located position is increased, and the plastic lens can be easily and accurately assembled in the constant direction on the basis of the concave surface, and the lens performance is stabilized and the assembling operability is also increased.
(2-6) The plastic lens described in any one of (2-1) to (2-5), in which the shortest distance between the virtual outer peripheral surface of the flange portion and the bottom portion of the concave surface is 0.15-0.25 mm.
According to the invention described in (6), when the shortest distance between the virtual outer peripheral surface of the flange portion and the bottom portion of the concave surface is 0.15-0.25 mm, in the detection of the gate-located position, specifically detection by eyes can be easily conducted, and the flange portion can not be excessively cut.
(2-7) In the plastic lens, a plastic lens in which the gate-located portion of the optical function portion is the concave surface.
According to the invention described in (2-7), because the gate-located portion of the optical function portion is the concave surface, and the position is definite by the concave surface, when the plastic lens is assembled to the optical apparatus, the detection of the concave surface can be easily conducted by eyes or the detector, thereby the detection accuracy of the gate-located position is increased. Therefore, the plastic lens can be easily and accurately assembled in the constant direction on the basis of the concave surface, and the assembling operability is increased and the optical performance is also stabilized.
(2-8) In the plastic lens, a plastic lens in which the outer peripheral portion of the optical functional portion has the gate-cut plane, and at least one portion of the gate-located portion of the gate-cut plane is the concave surface.
(2-9) In the plastic lens described in (2-8), all of the gate-located portion is the concave surface.
(2-10) In the plastic lens described in (2-8) or (2-9), the gate cutting surface other than the concave surface is the plane or the arc-shaped convex surface.
(2-11) In the plastic lens described in (9), all of the gate-cut plane is the concave surface.
According to the invention described in (2-8) to (2-11), because at least one portion of the gate-located portion of the gate-cut plane of the optical function portion is the concave surface, or all of the gate-located portion is the concave surface, the gate-cut plane other than the concave surface is the plane or arc-shaped convex surface, or all of the gate-cut plane is the concave surface, and the gate-located position is definite by the concave surface, when the plastic lens is assembled in the optical apparatus, the detection of the concave surface can be easily conducted by eyes and the detector, thereby, the detection accuracy of the gate-located position is increased. Therefore, the plastic lens can be easily and accurately assembled in the constant direction on the basis of the concave surface, thereby the assembling operability is increased, and the optical performance is stabilized.
Further, according to the invention described in (2-10), because, in the gate-cut plane other than the concave surface, the shape is the plane or the arc-shaped convex surface and different from the other portion, the gate-located position from the optical axis of the plastic lens becomes definite, and the gate-located position becomes definite also from the side surface of the plastic lens, thereby, the detection accuracy of the gate-located position is increased, and the plastic lens can be easily and accurately assembled in the constant direction on the basis of the concave surface, and the lens performance is stabilized and the assembling operability is also increased.
(2-12) The plastic lens described in any one of (2-7) to (2-11), in which the shortest distance between the virtual outer peripheral surface of the optical functional portion and the bottom portion of the concave surface is 0.15-0.25 mm.
According to the invention described in (2-12), when the shortest distance between the virtual outer peripheral surface of the optical functional portion and the bottom portion of the concave surface is 0.15-0.25 mm, in the detection of the gate-located position, specifically the detection by eyes can be easily conducted, and the optical functional portion can not be excessively cut.
(2-13) The plastic lens described in any one of (2-1) to (2-12), in which an angle formed between the linear line connected between the bottom portion of the concave surface and the optical axis in the shortest distance, and the linear line connected between the center of the gate-located portion and the optical axis in the shortest distance, is within 10xc2x0.
According to the invention described in (2-13), when the angle formed between the linear line connected between the bottom portion of the concave surface and the optical axis in the shortest distance, and the linear line connected between the center of the gate-located portion and the optical axis in the shortest distance, is within 10xc2x0, the bottom portion of the concave surface shows almost the central gate-located position, thereby, the central gate-located position becomes further definite. Specifically, when the plastic lens is assembled on the basis of the bottom portion of the concave surface, it can be accurately assembled, and the lens performance is further stabilized.
(2-14) The plastic lens described in any one of (2-1) to (2-13), in which the concave surface is the curved surface.
(2-15) The plastic lens described in (2-14), in which, when the concave surface is looked from the optical axis direction, it is arc-shaped.
(2-16) The plastic lens described in (2-15), in which the arc-shape is a portion of the circle whose radius is not larger than 1 mm.
(2-17) The plastic lens described in (2-14), in which, when the curved surface is looked from the optical axis direction, it is U letter-shaped.
According to the invention described in (2-14) to (2-17), when the shape of the concave surface is formed to the curved surface, the formation of the gate-cut plane including the formation of the concave surface becomes easy. Specifically, in the case where the curved surface is formed to arc-shaped or U letter-shaped when it is looked from the optical axis direction, the gate-cut plane which is the concave surface, is easily processed by the end-mill cutting machine. Further, when the arc-shape is a portion of the circle whose radius is not larger than 1 mm, the flange portion or the optical function portion can not be excessively cut.
(2-18) The plastic lens described in any one of (2-1) to (2-17), in which the concave surface is formed at the time of the formation of the gate-cut plane.
According to the invention described in (2-18), when the concave surface is formed at the time of cutting of the gate portion, the production of the lens can be quickly conducted.
(2-19) The plastic lens which has the almost arc-shaped concave surface at least at one portion of the outer periphery of the flange portion when viewed from the optical axis direction.
(2-20) The plastic lens which has the almost U letter-shaped concave surface at least at one portion of the outer periphery of the flange portion when viewed from the optical axis direction.
According to the invention described in (2-19) and (2-20), because, when the plastic lens is viewed from the optical axis direction, because the almost arc-shaped or almost U letter-shaped concave surface exists at least at one portion of the outer periphery of the flange portion, specifically when the plastic lens is viewed from the optical axis direction, a portion forming the concave surface of the lens can be made more distinct.
(2-21) A production method of the plastic lens, in which the gate-cut plane and the concave surface are formed by a common cutting means.
(2-22) A production method of the plastic lens, in which the gate-cut plane and the concave surface are formed by a series of cutting processes.
(2-23) A production method of the plastic lens, in which the gate-cut plane and the concave surface are formed by a common cutting means and a series of cutting processes.
According to the invention described in (2-21) to (2-23), when, as the cutting means for cutting the gate portion integrally formed with the plastic lens by the molding, and the cutting means for forming the concave surface, a common cutting means is used for forming the plastic lens, and these cutting are conducted by a series of cutting processes, it is not necessary that a plurality of cutting means are prepared, and the production can be conducted at low cost, and further, because it is conducted at one time, the plastic lens can be quickly produced.